406 THE ANNELIDA POLYCHAETA. 



Sternaspis affinis Stimpson, Proc. Acad. nat. sci. Philad., 1864, p. 159. 



Sternaspis assimilis Malmgben, Annulata Polychaeta, 1867, p. 87. 



Sternaspis islandica Malmgren, Op. cit., 1867, p. 87, pi. 14, fig. 85. 



f Sternaspis fossor Johnson, Proc. Bost. soc. nat. hist., 1901, 29, p. 418; Moore, Proc. Acad. nat. sci. 



Philad., 1908, p. 191. 

 Sternaspis costata Marenzeller, Denk. K. acad. wissensch. Math. -nat. klasse, 1879, 41, p. 142, taf. 



6, fig. 4. 



This species, as at present conceived, is widespread in the north Atlantic 

 and Pacific Oceans, at moderate depths. 



Locality. Gulf of Panama: Sta. 3391 (lat. 7° 33' 40" N., long. 79° 

 43' 20" W.). Depth 153 fms. Bottom of green mud. Bottom temp. 55.8° F. 

 9 March, 1891. Ten specimens. 



Sternaspis maior, sp. nov.^ 

 Plate 78, fig. 10. 



The type is badly broken, so that only the ventral plate or shield can be 

 satisfactorily studied. This plate, however, presents differences in structure 

 and is so much larger than that of S. fossor Stimpson, occurring off the coast of 

 British Columbia and Alaska and than the very closely related S. scutata (Ran- 

 zani) , occurring off Alaska and Japan, as well as in the Atlantic and Mediterra- 

 nean, that it seems obviously a distinct species. The plate is 15 mm. wide, 

 with a length along the median suture of 7 mm. and toward the ends of about 

 7.75 mm., the ratio of width to average length being two to one. The plate is 

 heavier and the sculpturing obviously coarser than in S. scutata or <S. fossor. 

 Each half of the anterior margin is straight, the two meeting at the middle in a 

 very obtuse reentrant angle. The ends are nearly evenly convex, with both the 

 anterior and caudal corners narrowly rounded. The caudal margin is nearly 

 straight, the inner portion of each half a little convex. The median longi- 

 tudinal furrow is deep and rather wide posteriorly. A strong ridge, beginning 

 as a broad fold at each caudolateral corner, runs obliquely across the half plate, 

 narrowing to a very fine point at the median line close to the caudal edge of the 

 anterior whitish part. Bordering this ridge on the caudomesal side is a deep 

 and wide furrow, the caudomesal region between this and the median furrow 

 being moderately convexly elevated and crossed by four much weaker furrows 

 parallel to the coarser one just mentioned. The region in front of each of the 



i^magnus, large. 



